Zero Morpheme

a linguistic unit isolated by opposing a word form without an affix to forms with positively expressed affixes. A form with a zero morpheme may be opposed to various forms in the same paradigm (stol, stola, stolu; the nominative, genitive, and dative of “table” in the singular), or there can be a single opposition (stol, stoly; the nominative singular and nominative plural of “table”). The zero morpheme has a definite grammatical significance.